How much power does it take to turn an alternator

[serialk11r]

Oh wait, does the generator slow down significantly when you start welding? I was thinking it was producing 80V, and then the generator would maintain the same rpm meaning you were dumping more than the rated current through the alternator stator, which is bad.

If that's the case I can see why people use alternator-welders, that is quite elegant. Mechanically producing higher voltage to start.

[oil pan 4]

It doesn't slow down a lot, less than 500rpm on an alternator that is spinning at up to 7,500rpm unloaded.
At lower welding amps it doesn't slow down much if any.

[oil pan 4]

My bad I got my stator mixed up. My old 10 and 12si alternators have very thick laminates. The newer AD244 and DR44G have very thin laminate plates.

[TimV]

Any testing done with stator current? But no electrical load?

[ar5boosted]

The counter question to this is how much Solar-Power or Cell-Size is needed to replace or augment this loss [in mechanical efficiency - due to cost cutting at the Alternator factory].

Personally I have a few small Solar Panels that I could easily junk out my cars with.

The question is really how much fuel am I wasting by not charging the battery with those small Solar Panels ?

[teoman]

There is some data on this in the mods pages. %5 if i remember correctly.

Depending on your driving habbits you may need a bigger battery and or biggish solar panels or charging at home.

It also depends vastly on your car. The consumption can be as low as 6 amps gor a purely mechanical setup to over a hundred amps with all the bells and whistles running simultaneously.

[oldtamiyaphile]

Originally Posted by ar5boosted

The counter question to this is how much Solar-Power or Cell-Size is needed to replace or augment this loss [in mechanical efficiency - due to cost cutting at the Alternator factory].

Personally I have a few small Solar Panels that I could easily junk out my cars with.

The question is really how much fuel am I wasting by not charging the battery with those small Solar Panels ?

I ran a 100Ah panel on my 1.6 for a couple of years. The factory alternator did a good job of keeping the battery full. On a sunny day the panel would be in float mode within a say ten minutes (100% city and 100% EOC). While my best tank was recorded with the panel, the overall gains aren't measurable against back ground noise. The main reason to do it is you have the convenience of not having to recharge your battery regularly.

Now if you have a smart alt and stop start, the gains are in the order of 0.5l/100km. I'm putting 360Wh on two of my cars (on with a smart alt - one will get an alt delete), I expect to see measurable gains.

[oil pan 4]

Yes energizing the armature with no load does load the alternator. But I don't know how much.
My little 5hp Honda powered alternator welder notices when I build up volts on the stator with not stator current load.